Gov. Deval Patrick on Friday kept his promise to veto a massive transportation financing bill, saying the measure was "not good enough" after lawmakers rejected his demand to include a plan for offsetting a potential loss of turnpike tolls.

In making the announcement, the governor said he was acting with "mixed emotions" because the bill included many positive elements.

Legislative leaders believe they have enough votes to override his veto.

Legislative leaders in both the House and Senate have expressed confidence that they have sufficient votes to override the veto.

The bill, which calls for $500 million in new taxes, seeks to pump billions of dollars into the state's transportation network over the next decade, allowing the state to modernize its aging infrastructure and jumpstart a number of stalled projects, such as expansion of commuter rail to the South Coast.

The legislation would also end the practice of borrowing to pay salaries of state transportation workers and close the MBTA's $115 million deficit, heading off another round of fare increases or service reductions.

"On the one hand, this bill, in its current form, enables us to reinvest in our transportation network, after decades of willful neglect," Patrick said in a statement. "It provides some short-term resources to deal with our most pressing needs. It responds to a key priority of my administration and will stimulate many jobs."

"But this bill is not good enough," he added.

The key flaw in the bill, according to Patrick, is that it does not address the problem of how to replace lost revenue if turnpike tolls west of Interstate 95 come down as scheduled in 2017. While some lawmakers are of the belief the tolls will not ultimately come down, the governor criticized the Legislature for choosing to deal with the question at a later time.

"I believe this is an issue to be dealt with now, not put off to another day," he said.

Patrick's amendment would have allowed for an automatic increase in the state's gas tax if — and when — the western tolls come down.

The House on Wednesday voted 121-31 to send the bill back to the governor without the change, and the Senate did the same on Thursday by a 29-9 margin. Both margins, if they held up, would be above the two-thirds threshold needed to override the veto.

The bill already includes a 3-cent-per-gallon increase in the gasoline tax and would index future increases in the tax to inflation. It also raises the cigarette tax by $1 per pack and imposes the state sales tax on computer software and services.

On the one hand, this bill, in its current form, enables us to reinvest in our transportation network, after decades of willful neglect. It provides some short-term resources to deal with our most pressing needs. It responds to a key priority of my Administration and will stimulate many jobs. I thank the Legislature for that.

But this good bill is not good enough.

The issue has to do with the fate of the western tolls, and whether we should deal now or later with a problem we can see coming. By current law those tolls come down in 2017, and the people who pay them have been assured they will come down. Some legislators say that the tolls will never come down, despite what the law now requires. Others say that the tolls must come down when scheduled, as a matter of fairness. The Legislature has chosen to deal with it later. That uncertainty makes it difficult to plan a steady, disciplined reinvestment plan sufficient to get the Commonwealth to where it needs to be.

I believe this is an issue to be dealt with now, not put off to another day. Transportation is too important to our citizens, their livelihoods, their quality of life, and our economy as a whole. And too often, those needs are only dealt with when they become a crisis. While this Administration and the Legislature have done much to improve on that record, and worked together successfully to address many challenges, I believe this good bill misses a critical opportunity for the people we serve.

For these reasons, I will not support it.

This program aired on July 19, 2013. The audio for this program is not available.